<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="app">
    <ul>
      <li v-for="(item,index) in arr">{{item}} <button @click="del(index)">删除</button></li>
    </ul>
    <button @click="fn()">添加</button>
  </div>
  <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
  <script>
    const vm = new Vue({
      el:'#app',
      data:{
        arr:[]
      },
      methods: {
        fn(){
          this.arr.push(Math.ceil(Math.random()*20))
        },
        del(i){
           this.arr.splice(i,1)
        }
      },
    })
  </script>
</body>
</html>